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One Year Later

A Review of Harvard Transit’s Electric Bus Roll-Out

By John W. Nolan, CAPP

Overview

Over the last two years, I have written about Harvard University transforming its vehicle fleet, starting with four EV (electric vehicle) buses, and launching a “living lab” to study their effectiveness. We are sharing the results comparing our initial proforma between internal combustion engines (ICE) and our EVs.

Before we committed to a complete overhaul of all 15 buses, we wanted to understand better overall costs with a performance comparison in MPGe, energy consumed, maintenance performed, and emissions avoided within our four-season environment. In addition, we wanted to compare the charging efficiency, and emissions output of the EV buses compared to the advertised expectations from the manufacturer. Director of Transit and Fleet Management David Harris, Transportation IT Project Manager John Pelletier, and I are now sharing results and learning experiences during the first year of operation.

Our shuttle bus fleet transports approximately 600,000 students across Harvard’s campuses each year. “Transitioning buses to electric power showed a reduction in greenhouse gas emissions by 220,462 pounds (or 40 MTCDE) annually. Two key air pollutants, which are very harmful to human health, were also reduced; particulate matter (PM2.5) by 0.013 metric tons and nitrogen oxides (NOx) by 0.752 metric tons annually. These reductions are the equivalent of removing 12 gasoline-powered cars from the road for one year.”1

This project was made possible through a generous grant from the State of Massachusetts which has funded around 100 projects across the Commonwealth to help electrify the transportation sector, a zero-interest loan from the Harvard Green Revolving Fund which funded the level 3 charging system, as well as an internal 3% capital loan from the Office of Treasury Management for the financing of the EV buses. These lower cost funding streams enabled the bus acquisition, and charging system infrastructure which is necessary to support the new vehicles, to be totally funded through our operating budget.

Summary Usage Data

As part of this program, Harvard Transit and Fleet studied performance metrics, MPGe, and miles driven in our (4) Proterra 35’ Catalyst E2 440 kWh buses for the one-year period of February 3rd, 2022, through February 2nd, 2023.

February 3rd, 2022, through February 2nd, 20232
EV-1 EV-2 EV-3 EV-4 Total Description
Odometer Sum (mi) 14,701 3,854 14,608 12,954 46,117 Sum of odometer
Charging Port Energy (kWh) 40,886 14,547 40,009 39,834 135,276 Charging energy measured at the Combined Charging System (Combined Charging System) port
Net Charging Energy (kWh) 34,832 11,627 34,482 32,726 113,667 Charging energy measured at the batteries
Cumulative Energy Consumption (kWh/mi) 2.37 3.01 2.37 2.53 2.47 Cumulative energy consumption rate when not plugged into a CCS port
Cumulative MPGe 15.7 12.4 15.8 14.8 15.1 Cumulative B20 diesel equivalent fuel economy when not plugged into a CCS port based on 37.037 kWh per diesel gallon

*EV2 was out of service for repairs due to an accident in February 2022

February 3rd, 2022, through February 2nd, 20232
EV-1 EV-2 EV-3 EV-4 Total Description
Odometer Sum (mi) 14,701 3,854 14,608 12,954 46,117 Sum of odometer
Charging Port Energy (kWh) 40,886 14,547 40,009 39,834 135,276 Charging energy measured at the Combined Charging System (Combined Charging System) port
Net Charging Energy (kWh) 34,832 11,627 34,482 32,726 113,667 Charging energy measured at the batteries
Cumulative Energy Consumption (kWh/mi) 2.37 3.01 2.37 2.53 2.47 Cumulative energy consumption rate when not plugged into a CCS port
Cumulative MPGe 15.7 12.4 15.8 14.8 15.1 Cumulative B20 diesel equivalent fuel economy when not plugged into a CCS port based on 37.037 kWh per diesel gallon

*EV2 was out of service for repairs due to an accident in February 2022

After comparing this data to the kWh billed by our energy provider Eversource, we could see the overall inefficiencies of the charging system from “pole to port.”

As demonstrated in the table below, the energy delivery system from the pole through the transformer, switchgear, copper raceway, bus chargers, bus dispensers, and then into the bus via the CCS port accounted for 26% of the energy consumed during this study period.

kWh billed by Eversource 149,064
kWh consumed by Harvard charging infrastructure 38,896
kWh consumed as a percentage 26%

Our study also revealed the necessity of pre-conditioning during colder winter months, which was previously unknown by us. This process draws additional energy to engage the bus systems, chargers, and batteries and keeps the system operating at optimum temperatures. Approximately 7% of our kWh went into pre-conditioning. Eversource charges more for daytime peak hour charging, which negatively impacts our overall costs. Furthermore, the average kWh/mile in December-April increased by 50%, limiting our ability to drive the needed routes or total mileage with one charge. This is reflected in our proforma with estimated miles driven of 25K versus the 14k actual miles driven. In other words, our ICE buses needed to fill in on planned EV bus routes due to battery insufficiency during cold weather days.

B20 Diesel Cost Compared to Electricity Cost

A critical component of the fleet electrification process is understanding the source and costs related to electricity. At Harvard, we have Eversource providing distribution coupled with Harvard Dedicated Energy Limited (HDEL) for energy supply. Harvard University formed HDEL to serve the electric needs of Harvard’s schools and departments. HDEL provides access to the wholesale electric market and greater flexibility to meet supply needs. HDEL’s goal is to purchase energy in an economically efficient manner while appropriately managing risk and price volatility. 

When the actual cost of diesel during this study period is compared to the actual cost of electricity, electricity was 52% more expensive than diesel. A good part of this expense was attributed to the timing of when the buses were charged. There is a remarkable cost difference to charging during daytime hours vs. nighttime hours, which is a significant contributor to the costs shown in the following table.

Actual cost of electricity3 at an average $.53/kWh $78,596
Cost of diesel + diesel exhaust fluid4 $51,798
Difference of electricity vs. diesel $26,798

Midway through this study period, in the fall of 2022, we learned that additional electric costs could be avoided by restructuring the timing of our charging process as well as reconfiguring our dispensers to limit peak demand during the day.

We projected at that time this charging realignment process would result in an annual savings of $6,779 or 13% based on existing electricity rates. This difference would be based on the demand for services and the overall daily usage of our EV buses.

Adjusted cost of electricity projected ($.30/kWh) $45,019
Difference of electricity vs. diesel ($6,779)

*After the study period ended on July 1, 2023, Eversource restructured its rates, significantly reducing its peak demand charges. If this change had previously been implemented, energy costs would have been 52% more expensive to 45% less expensive. This action was taken to incentivize electric vehicle purchases. Based on costs as of April 2024, the table below shows what our savings would have been during the study period.

*Adjusted cost of electricity ($.19/kWh) $28,322
Difference of electricity vs. diesel ($23,476)

As seen in the above tables, the cost of electricity is influenced by how one operates the total system and the incentives provided by the local utility. While the overall cost of acquisition and operation may exceed that of ICE buses, the health benefits, noise remediation benefits, and community goodwill could be much more valuable to an operating agency.

“Motor vehicles are a large source of NOx emissions, which lead to fine particulate matter (PM) pollution in the atmosphere, these emissions are especially a problem in dense urban areas with lots of traffic. Exposure to fine PM has been directly associated with premature mortality and a suite of other adverse health effects.”

—Elsie Sunderland, Gordon McKay Professor of Environmental Chemistry at Harvard John A. Paulson School of Engineering and Applied Sciences and Professor of Environmental Science and Engineering at the Harvard T.H. Chan School of Public Health.

The Road Ahead: Completing the Transition of Harvard’s Bio-Diesel Shuttle Fleet to Electric by 2035

Harvard University is preparing to add two more EV buses to its existing bus fleet. We will also double our charging capacity to enable this and future expansion. We learned a lot of lessons in the first year of our operation that can now be applied to us and others interested in following this path forward. We continue to follow our goals as stated below:

Harvard’s Ongoing Sustainability Goals

  • Complete the transition of Harvard’s shuttle-bus fleet to all-electric by 2035.
  • Set new target dates for the remaining fleet vehicle types by the end of 2026 as part of the University’s commitment to be fossil fuel-free by 2050.
  • Create a roadmap that includes an outline for installing more charging infrastructure for university vehicles and equipment.
  • Install adaptable load management (ADM) systems that enhance existing electrical infrastructure to deliver efficient charging to more vehicles.

To summarize our lessons learned:

  • Understanding the operational learning curve is necessary for your EV operation. Implementation costs for training and transitioning from ICE to EV for your drivers and fleet staff should be budgeted as part of your project soft costs.
  • Constructing a Level 3 charging project can take up to 18 months from planning and coordinating through field design, engineering design, permitting the project, and coordinating with external contractors and your local utility.
  • Remediation of soil conditions can add significant expense to your project.
  • Plan for less MPGe than the manufacturer estimates. Our mile per gallon equivalent of 15.1 was lower than the projected 17 MPGe, but it was much better than the 4.3 MPG for ICE buses.
  • Managing the timely delivery of electricity can save substantial costs.
  • Investing in software for energy distribution, pre-conditioning, and charge management as part of this electrical system will reduce the cost of employee participation for redeployment to other, more relative work.
  • Annual electric bus operating costs are slightly less expensive than diesel.
  • Our payback period is about 10.5 years based on current purchase prices but will become more favorable if prices come down in the future.

It is important to state that no two operations are alike. Your operation is unique, and transit operations have different fleet sizes, dimensions, ages, and types. However, you can review our data and methodology to get an indication of potential outcomes to expect and pitfalls to avoid.

We hope this information and study are helpful to you moving forward. If you have any questions about this information, do not hesitate to reach out. ◆

References
  1. Harvard Office for Sustainability
  2. Data provided by Proterra Project Engineer, May 1st, 2023.
  3. Harvard Engineering and Utilities, 28 Travis St Bus Charging Station—Monthly Billing Details
  4. Actual usage and cost from Harvard Vendor invoices
Managing Director of Transportation | 

John W. Nolan, CAPP, is the Managing Director of Transportation Services and The Campus Service Center for Harvard University and a member of the IPMI Planning, Design, & Construction Committee.

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